Gas cable installation



Aug. 19, 1941. F. w. ENGSTER 2,253,171

6A5 CABLE INSTALLATION I Filed June 6, 1940 A: v GAS FILLED 0" I} o oi mmmnaw lnventori Prank W En star,

His; Attorney PatentedAug. 19, 1941 7 2,253,171 GAS CABLE ms'ranm'rrou Frank W. Engster, Mount Vernon, N. Y., assignor to General Electric Company, a corporation oi New York I Application June 6, 1940, Serial No. 339,133

4 Claims.

The present invntion relates to gas filled cables of the type in which the insulation, such as paper, on the conductors is impregnated with a compound that is retained therein by capillary action and which has little tendency to ooze from the insulation even under-load cycles. At suitably disposed places within the cross-section of the cable are located Iree'ieed gas conveying channels which in addition to conveying gas to the insulation also serve as conduits for conveying any compound oozing out of the paper to selected points such as the joint casings. It frequently happens that there are low spots or areas ot'the cable occasioned by dips therein to avoid obstructions in the path of the cable such as water, illuminating gas and other pipes, or the dips may be due to the rugged profile of the ground in which the-cable is laid. Such a dip or low spot may cause compound to collect in the free teed gas channels in an amount sumcient to form slugs which interfere with the free movements the insulating gas. To prevent the effects of such slugs on the free fiow oi! gas a small solid wall tube extending from end to end the cable is located at some convenient place in the cross-section of each cable length and through which gas may flow from suitable tanks from end to end of a cable section if stop joints are employed to sectionalize the cable, or from end to end of the cable it stop joints are not employed.

It is important to provide means whereby access may be had tothese tubes withoutopening or removing the joint casings or injuring them in any way. Such access is necessary for various purposes, including testing for gas leaks in the cable enclosures. It is also important to arrange the ends of the tubes entering the joint casing from connected lengths of cable in such manner that any compound within the joint casing is prevented from entering the tubes where its presence would cause stoppagethereoi and thus defeat the purpose of the tube which is to bypass any slugs of compound located in low areas and ensure free flow of gas between widely separated points, asterminals for example.

The object of my invention is the provision of improved simplified means or arrangement oiparts whereby access may be had to the solid wall gas conveying tubes located with the cable proper and in the Joint casing without disturbing the casings, and. whereby independent control 0! each of the gas tubes may be obtained as well as the admission of gas to the joint casing.

For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the drawing, Fig. 1 illustrates a normal joint with the gas conveying solid wall tubes terminatby the plug I5.

\ on line 22 oi. Fig. 1.

The conductors are indicated byreference numerals I, 2 and 3 and the joints therefor by l, 5

and l. Surrounding each of the conductor length's is an impervious sheath 1 of lead or equivalent material. In the so-called filler spaces between the surfaces of the conductors and the inner wall of the sheath are free feed gas conveying channels. In the case of three conductor cables, as here shown, there are three of these channels. In two of them are located members I in the form of long coiled springs while in the third is located a solid wall gas conveying tube 9. The channels open into the joint casing above the level of any compound collected therein. It indicates the chambered casing which encloses the joints and has its ends secured to the sheaths by wipe soldered joints Ii. The dotted line Illa indicates compound collected in the casing. The casing. maybe made in one piece or it may be divided into two or. more parts as is customary with joint casing structures. When made in a single piece, the ends of the gas tubes 9 and 9a are first pulled throughthe opening l3 in the casing and later threaded through the tube openings in the fitting ii. The casing opening l3 located on the upper side about midway of its length is closed by the chambered fitting l2 that is soldered to the wall thereof in a' gas tight manner. The casing is also provided with an opening which is sealed by a plug I4 and through which gas may be supplied to the cables. It is also provided with a drainage opening sealed The lengths of the cable as above stated have solid wall gas conveying tubes 9 and 9a the ends of which are trained upwardly in a manner to enter the fitting II.

The fitting i2 is of tubular form having a portion l5 extending through the opening in the casing and a shoulder II which rests on'the casingwall and is soldered thereto to make a gas tight seal. It is advantageous to make the base of the fitting small so that the area of the joint is correspondingly small as such joints are more easily made tight than large ones. It is also advantageous to locate the fitting on the top oi! the casing to facilitate the soldering operation and to facilitate inspection. In the bottom wall I! of the fitting are two openings through which the upper ends 01 the solid wall tubes 9 and 9a extend. After the ends of the tubes are properly is provided which is left open when it is desired to admit gas, such as nitrogen, to the casing chamber. When it is. not so desired, it is closed by a screw threaded/plug 20. The tube ends have caps 2| and 22 which may or may not be used as desired. The fitting is provided with a closure 23 which is screw threaded thereto and between the two is a suitable packing 24.

When it is desired to gain access to tube 9 only, as for testing for example, the closure 23 is removed and cap 22 applied to the end of tube 9a. Ii it is desired to gain access to tube 9c, only the cap 2| is applied to tube 9. With both tubes 9 and 9a uncapped and the closure 23 in place, the tubes are connected in series relation. It is to be understood that as many cable lengths as desired may be connected in this manner. In the usual installations, a considerable number of joints and joint casings will be required. If it be desired to fill the joint casing with gas under positive pressure from the tubes 9 and 9a, the plug will be removed. When in place, the plug shuts off communication between the tubes and the chamber of the casing. When a joint casing has of necessity to be located at or near a low spot in the cable when the level of the compound may be unduly high, it is desirable to have the plug 20 screwed into place to prevent compound from flowing from the easing into the filling. In this manner, it is possible definitely to shut off all communication between the tubes and the joint casing. Even if the casing is completely filled with compound due to drainage, none of it can enter the tubes. For filling the casing or casing and the free feed channels with gas under positive pressure, the plug l4 may be removed and a gas pipe screwed into place either as a temporary or permanent part. The arrangement above described has the advantage that the solid wall tubes can be controlled at will and by a very simple means. When the caps 2| and 22 are removed, and the plug 20 in place, the joint is by-passed and gas flows freely from one tube to another. By capping the end of one tube and leaving the other open, the plug 20 being in place, the tubes may be independently supplied with gas under pressure from joints located at remote points. Under these conditions, gas may be supplied independently to the joint casing and to the free gas channels in the cable lengths. Gas may be supplied to one or more of the casings depending upon the length of the cable installation. i

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A cable installation comprising lengths of gas filled sheathed cable, each length: having compound impregnated insulated conductors,

free feed channels for conveying gas and also compound oozing from the insulation, and a solid wall tube for by-passing any compound collected in the channels, the tube containing gas under positive pressure, joints between adjacent conductor lengths, a. chambered casing enclosing the joints and sealed at its ends to adjacent sheaths and -into which the channels open, a chambered fitting secured'to the wall of the casing, both of the tubes of adjacent lengths terminating and sealed in place within the fitting and having normally open ends permitting gas to flow through thechamber from one tube to the other in series relation, a removable cap for the open end of at least one of the tubes whereby communication between them through the chamber of the fitting prevented, a controllable port in the fitting through which gas may flow between the chamber of the fitting and that of the casing, and a closure for the fitting.

2. A cable installation comprising lengths of gas filled sheathed cable, each lengths having compound impregnated insulated conductors, free feed channels for conveying gas and compound oozing from the insulation and a solid wall tube for by-passing any compound collected in the channels, the tube containing gas under positive pressure, joints between adjacent conductor lengths, a chambered casing enclosing the joints and sealed at its ends to adjacent sheaths and into which the channels open, a chambered fitting secured to the wall of the joint casing having openings to receive the ends of the tubes of adjacent cable lengths located within the joint casing and in which the tubes terminate and are supported thereby, a port in the fitting independent of the tubes opening from the chamber thereof into the joint casing, and means whereby the flow of gas through the port from the tube ends and chamber into the joint casing may be controlled.

3. A cable installation comprising lengths of sheathed cables, each length having a compound impregnated insulated conductor and a. free feed channel for conveying gas to the insulation and receiving compound oozing from the surface of the insulation under load conditions, a joint between each pair of adjacent conductor lengths, a chambered casing enclosing the joint and having an opening in its wall between the ends thereof, the casing being sealed at its ends to adjacent sheaths and receiving compound from the channels and also gas under positive pressure, a chambered fitting secured to the wall of the casing and covering the opening therein, a solid wall tube in each cable length for by-passing slugs of compound in the channel thereof, the portions of the tubes beyond the sheath ends being located within the joint casing with the may flow between the chamber of the fitting and that of the casing.

4. A cable installation comprising lengths oi sheathed cables, each length having a compound impregnated insulated conductor and afree feec channel for conveying gas to the insulation anC receiving compound oozing from the surface 01 the insulation under load conditions, a joint between each pair of adjacent conductor lengths, a chambered casing enclosing the joint and having an opening in its wall between "the ends thereof the casing being sealed at its finds to adjacenl sheaths and receiving compound from the channels and also gas under positive pressure, a chambered fitting secured to the wall of the cas ing and covering the opening therein, a solic' wall tube in each cable length for by-passing slugs of compound in the channel thereof, the portion of the tubes beyond the sheath ends being located within the joint casing with the end: thereof secured in and projecting through a. wall of the fitting into its chamber to permit the flow of gas between the tubes, the casing and fitting completely enclosing and protecting the tube: beyond the ends of the sheaths, means in th( fitting for closing or opening the ends of the tubes to control the how of gas therethrough and a controllable port in the fitting througl which gas may flow between the chamber of th: fitting and that or the casing.

FRANK W ENGSTER 

